Transcript for Anatomy of a Hostage Rescue: Inside the Alabama Bunker Raid

As we come on the air, new details are streaming in about the daring secret operation that freed a little boy, locked in a bunker for seven long days. How did they free him? Well, tonight, we are hearing reports of a gun fight, as they moved in to save a child. Abc's gio benitez following it all for us. Reporter: The little boy at the center of a week-long hostage standoff is in his mother's arm, and tonight, the fbi's bold plan to rescue him coming into sharp focus. Negotiators convinced jimmy lee dykes to approach the bunker door to accept delivery of an item. There, fbi agents set off an explosive device. Law enforcement officers say dykes fired on the agents. They fired back. Moments later, dykes was dead and ethan was safe. The fbi and highly specialized s.W.A.T. Teams spent seven days planning the raid, while hostage negotiators tried to keep dykes talking. We boarded a hall continuer here in southern alabama to get our first look at dykes' underground bunker site. You can see a number of small structures on this plot of land. But what dykes didn't know, just across the street, the fbi had recently built this mock bunker to train agents for different scenarios. You can practice breaching the door. You can practice how to get a camera inside. And ultimately design how you're going to assault this bunker. Reporter: As authorities swarmed the ground above, hostage negotiators remained in contact with dykes, speaking through a ventilation pipe. Authorities were able to sneak a small camera inside the six by eight foot bunker to monitor dykes' movements. Then, when authorities saw dykes becoming increasingliage talted and holding a gun, they put their plan into action. Now ethan is recuperating from his ordeal. Just moments ago, we received a letter from ethan's mom. She says for the first time in a week, she woke up to a beautiful sight this morning -- her sweet little boy. Diane? And we love looking at his face and his smile. But gio, let me go back for a moment. The man with a gun, he had a television. He could see what he was reporting. And he had no idea, right out of frame, behind you, commandos preparing for this raid? Reporter: In fact, they were training right next to the media here. All right, well, thank you so much, gio.

This transcript has been automatically generated and may not be 100% accurate.

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